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Pneumonia is an infection of the lungs that is caused by bacteria, viruses, and, less often, fungi. Globally, pneumonia causes more deaths than any other infectious disease, such as AIDS, malaria or tuberculosis.

In the U.S., the most common bacterial cause of pneumonia is Streptococcus pneumoniae (pneumococcus) and the most common viral causes are influenza, parainfluenza, and respiratory syncytial viruses. In children less than 1 year of age, respiratory syncytial virus (RSV) is the most common cause of pneumonia.


Pneumonia can cause mild to severe illness in people of all ages. Signs of pneumonia can include coughing, fever, fatigue, nausea, vomiting, rapid breathing or shortness of breath, chills, or chest pain.


Physical Exam

Your doctor will listen to your lungs with a stethoscope. If you have pneumonia, your lungs may make crackling, bubbling, and rumbling sounds when you inhale. It may be hard to hear sounds of breathing in some areas of your chest. Your doctor also may hear wheezing.

Diagnostic Tests

If your doctor suspects you have pneumonia, he or she also may order one or more of the following tests.

Chest X Ray

A chest x ray is a painless test that creates pictures of the structures inside your chest, such as your heart and lungs. It is the best test for diagnosing pneumonia. However, this test won’t tell your doctor what kind of germ is causing the pneumonia.

Blood Tests

Blood tests involve taking a sample of blood from a vein in your body. A complete blood count (CBC) measures many parts of your blood, including the number of white blood cells in the blood sample. The number of white blood cells can show whether you have a bacterial infection.

Your doctor also may order a blood culture to find out whether the infection has spread to your bloodstream. This test is used to detect germs in the bloodstream. It may show which germ caused the infection. If so, your doctor can decide how to treat the infection.

Other Tests

You may need other tests if you’re in the hospital, have serious symptoms, are older, or have other health problems.

Sputum test. Your doctor may look at a sample of sputum (spit) collected from you after a deep cough. This may help your doctor find out what germ is causing your pneumonia . Then, he or she can plan treatment.

Chest CT scan. A chest CT scan is a painless test that creates precise pictures of the structures in your chest, such as your lungs. A chest CT scan is a kind of x ray, but its pictures show more detail than those of a standard chest x ray.

Pleural fluid culture. For this test, a sample of fluid is taken from the space between your lungs and chest wall (the pleural space). This is done using a procedure called thoracentesis. The fluid is studied for germs that may cause pneumonia.

Pulse oximetry. For this test, a small clip is attached to your finger or ear to show how much oxygen is in your blood. Pneumonia can keep your lungs from moving enough oxygen into your bloodstream. If you’re very sick, your doctor may need to measure the level of oxygen in your blood using a blood sample. The sample is taken from an artery, usually in your wrist.

Bronchoscopy. Bronchoscopy is a procedure used to look inside the lungs' airways. If you’re in the hospital and treatment with antibiotics isn’t working well, your doctor may use this test. Your doctor passes a thin, flexible tube with a camera on its tip through your nose or mouth, down your throat, and into the airways. This test allows your doctor to see whether something is blocking your airways or whether another factor is contributing to your pneumonia.


Treatment for pneumonia depends on the type of pneumonia you have and how severe it is. Most people who have community-acquired pneumonia—the most common type of pneumonia—are treated at home.

The goals of treatment are to cure the infection and prevent complications.

General Treatment

It’s important to follow your treatment plan, take all medicines as prescribed, and get ongoing medical care. Talk to your doctor about when you should schedule followup care. Your doctor may want you to have a chest x ray to make sure the pneumonia is gone.

Although you may start feeling better after a few days or weeks, fatigue (tiredness) can persist for up to a month or more. People who are treated in the hospital may need at least 3 weeks before they can go back to their normal routines.

Bacterial Pneumonia

Bacterial pneumonia is treated with antibiotics. You should take antibiotics as your doctor prescribes. You may start to feel better before you finish the medicine, but you should continue taking it as prescribed. If you stop too soon, the pneumonia may come back.

Most people begin to improve after 1 to 3 days of antibiotic treatment. This means that they should feel better and have fewer symptoms, such as cough and fever.

Viral Pneumonia

Viral pneumonia isn’t treated with antibiotics. This type of medicine doesn’t work when a virus causes the pneumonia. If you have viral pneumonia, your doctor may prescribe an antiviral medicine to treat it.

Viral pneumonia usually improves in 1 to 3 weeks.

Treating Severe Symptoms

You may need to be treated in a hospital if:

  • Your symptoms are severe
  • You’re at risk for complications because of other health problems.

If the level of oxygen in your bloodstream is low, you may receive oxygen. If you have bacterial pneumonia, your doctor may give you antibiotics through an intravenous (IV) line inserted into a vein.


Vaccines are available to prevent pneumococcal pneumonia and the flu. Vaccines can’t prevent all cases of infection. However, compared to people who don’t get vaccinated, those who do and still get pneumonia tend to have:

  • Milder cases of the infection
  • Pneumonia that doesn’t last as long
  • Fewer serious complications



National Heart, Lung, and Blood Institute, USA.

Centers for Disease Control and Prevention, USA.